Corona discharge treatment of polymer film to increase the adhesion characteristics thereof



March 31 1970 A. A. GoNcARovs ETAL 3,503,859

CORONA DISCHARGE TREATMENT Q1` POLYMER FILM TO INCREASE y THE ADHESION CHARACTERISTICS THEREOF Filed May 2, 1967 United States Patent O 3,503,859 CORONA DISCHARGE TREATMENT OF POLYMER FILM VTO INCREASE THE ADHESION CHARAC- TERISTICS THEREOF Askolds A. Goncarovs, Milford, Herbert O. Corbett, Bridgeport, and John J. Quackenbnsh, Monroe, Conn., assignors to National Distillers and Chemical Corporation, New York, N.Y., a corporation of Virginia Filed May 2, 1967, Ser. No. 635,604 Int. Cl. B44d 1/092 U.S. Cl. 204-165 2 Claims ABSTRACT F THE DISCLOSURE A plastic film or sheet treating apparatus having a plurality of rollers through which a plastic web travels. Alternate rollers are movable from a plane on one side of the web to a position on the other side of the web. The web is threaded straight between the fixed rollers and the lowered movable rollers. The movable rollers are then moved upwardly to obtain the desired looped arrangement of the web with appropriate wrap of the web, and web tension being obtained around the roller or rollers adjacent one or more treating electrodes.

This invention relates to the surface treatment of plastic lm and sheet, and more particularly to an arrangement of a plurality of rollers for looping a plastic web so that the web is appropriately wrapped around the rollers adjacent treating electrodes with suitable tension, wherein the web can be threaded straight through the roller arrangement with alternate rollers subsequently moving perpendicular to the web, to cause the web to partially wrap around each roller.

It is common knowledge that the surface of plastic film or sheet should be electrostatically treated so that the surface can be printed upon, or coated in a later stage. Electrostatic treating apparatus typically includes a system of rollers which are arranged to force the web to wrap partially around each of the rollers. One or more of the rollers are adjacent to electrostatic treating electrodes, so that as the web surface moves past the electrode, it will be suitably treated by exposing one or both web surfaces to corona discharge from the treating electrodes. It has been a problem in the past to thread the web through the roller system because of the festooning type pattern which the web must travel. In accordance with the present invention, alternate rollers of the system are mounted to have motion perpendicular to the plane of the web. When threading the web, the alternate movable rollers are moved below the plane of the fixed rollers, and the web is threaded straight through and between the iiXed rollers and movable rollers. Thereafter, the movable rollers are each moved upward to form the desired festooned path to obtain the web tension and the desired wrap of the web over the rollers which are located adjacent treating electrodes.

It is, therefore, a primary object of this invention to simplify the threading of a web of plastic material in an electrostatic treating apparatus.

Another object of this invention is to automatically obtain a desired wrap around a roller in an electrostatic treating apparatus by using movable rollers in an electrostatic treating apparatus by using movable rollers which move generally perpendicular to the path of travel of the web.

These and other objects of this invention will become apparent from the following description when taken in connection -with the drawings in which:

FIGURE 1 is a perspective diagram of a treating aplee paratus for electrostatically treating the surfaces of a web with the rollers in their festooned position.

FIGURE 2 is a side view of the roller system of FIG- URE 1, illustrating the movable rollers in their retracted position, with the web threaded straight through the apparatus, and with the final position of the rollers shown in dotted lines.

FIGURE 3 is a side View of one of the movable rollers of FIGURE 2 to illustrate the connection of piston rods to both ends of the roller.

Referring first to FIGURE 1, there is illustrated a plastic web 10 which travels through the treating apparatus in the direction of the arrows and is looped over and under rollers 11 to 16 in the manner well known in the art. The web 10 cornes from some suitable supply (not shown) and is rolled up on a storage roll 17. In order to electrostatically treat the surface of web 10, elongated electrodes 18 and 19 are placed adjacent rollers 12 and 15, respectively. Electrodes 18 and 19 are then connected to some suitable source of potential which is connected between leads 20 and 21 and grounded rollers 12 and 15. As the lower surface of web 10` passes above electrode 18, it will be electrostatically treated in the usual manner, while the upper surface of web 10- will be treated by passing under electrode 19.

In accordance with the present invention, the rollers 12, 14 and 16 are yfixed in position, while the alternate rollers 11, 13 and 15 are movably mounted from the lower, solid line position shown in FIGURE 2 to their inal position, as shown in FIGURE 1 and shown in dotted lines in FIGURE 2. It will be noted that the treating electrodes 18 and 19 are stationarily positioned.

Each of rollers 11, 13 and 15 are connected at their opposite ends to piston rods, shown as piston rods 20, 21 and 22 for rollers 11, 13 and 16, respectively. Clearly,

each end of the rollers will be mounted in this manner,

as illustrated in FIGURE 3 for the case of roller 11 which receives rod 20 at its left-hand and a similar rod 23 at its right-hand end.

Referring to FIGURE 2, each of piston rods 20, 21 and 22 are connected to pistons 24, 25 and 26, respectively, which are carried in cylinders 27, 28 and 29, respectively. The bottom of each cylinder 27, 28 and 29 contains openings 30, 31 and 32, respectively, which can be connected to a suitable hydraulic operating system (not shown) for operating pistons 24, 25 and 26, in order to cause rollers 11, 13 and 15 to move upwardly to their dotted line position.

In operation, the web 10 of FIGURE 2 is first threaded straight through and between the roller set 12-14-16 and roller set 11-13-15 -when the pistons 24 to 26 are in the bottom of their respective cylinders and the rollers 11, 13 and 15 are in their lowest position. Note that the Iweb 10 must be threaded between treating electrode 18 and roller 12. After this simple threading process, the hydraulic system (not shown) is activated to move pistons 24 to 26 upwardly, thereby disposing the web in the desired manner, as illustrated in FIGURE l, so that the system can become immediately operative.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an eX- clusive privilege or property is claimed are defined as follows:

1. The process for electrostatically treating both sides of a plastic web while passing said web through a plurality of sequentially spaced rollers which includes the steps of lowering alternate rollers of said plurality of rollers below the horizontal level of the remaining rollers; providing a first electrostatic treating zone immediately beneath one of the said remaining rollers and above the level of said lowered rollers; passing said plastic web straight through the region above said .lowered rollers and beneath the remaining rollers and through said irst electrostatic treating zone while effecting a corona discharge in said rst zone whereby the lower surface of said plastic web is caused to receive electrostatic treatment; raising said alternate lowered rollers above the horizontal level of said remaining rollers thereby causing said web to at least partially wrap around each of said rollers; and providing a second electrostatic treating zone directly above the path of movement of one of said lowered rollers immediately adjacent the upward limit of movement thereof while eiecting a corona discharge in said second zone whereby the upper surface of said plastic web is caused to receive electrostatic treatment.

2. Apparatus for electrostatically treating both sides of a plastic web which passes therethrough, said apparatus comprising a tirst plurality of fixed, elongated, longitudinally spaced rollers disposed in a single plane; a second plurality of elongated, longitudinally spaced rollers positioned in alternating relationship with respect to said first plurality of rollers; said second plurality of rollers being movable transversely through the plane of said first plurality of rollers from a retracted position on one side of said plane to an operative position on the other side of said plane; mounting means adjacent the extremities of each roller of said second plurality of rollers; means associated with said mounting means for selectively moving the rollers of said second plurality of rollers from a retracted position to an operative position; a rst elongated electrode treating means mounted immediately beneath one roller of said first plurality of rollers for electrostatically treating the lower Surface of a plastic web which travels above said first elongated electrode treating means and beneath said roller; and a remotely located elongated electrode treating means positioned in alignment with one roller of said second plurality of rollers and mounted adjacent to the operative position of said roller for electrostatically treating the upper surface of a plastic Iweb which travels beneath said second elongated electrode treating means and above said last mentioned roller.

References Cited UNITED STATES PATENTS 2,098,387 11/1937 Heine 226-13 2,524,064 10/ 1950 Masterson 226-189 2,969,463 l/ 1961 McDonald 204-165 3,109,572 ll/ 19613 Herr 226-189 ROBERT K. MIHALEK, Primary Examiner U.S. C1. X.R. 

